Excerpt: ...greenness is due to its chlorophyll, and it undoubtedly has the manufacturing power in full degree, decomposing carbonic acid and setting oxygen free, under the influence of sunlight. But the protoplasmic contents of some of the cells of which the plant is made up occasionally divide, by a method similar to that which effects the division of the contents of the Peronospora spore; and the severed portions are then set free as active monad-like zoospores. Each is oval and is provided at one extremity with two long ...
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Excerpt: ...greenness is due to its chlorophyll, and it undoubtedly has the manufacturing power in full degree, decomposing carbonic acid and setting oxygen free, under the influence of sunlight. But the protoplasmic contents of some of the cells of which the plant is made up occasionally divide, by a method similar to that which effects the division of the contents of the Peronospora spore; and the severed portions are then set free as active monad-like zoospores. Each is oval and is provided at one extremity with two long active cilia. Propelled by these, it swims about for a longer or shorter time, but at length comes to a state of rest and gradually grows into a Coleochaete. Moreover, as in the Peronospora, conjugation may take place and result in an oospore; the contents of which divide and are set free as monadiform germs. If the whole history of the zoospores of Peronospora and of Coleochaete were unknown, they would undoubtedly be classed among "Monads" with the same right as Heteromita; why then may not Heteromita be a plant, even though the cycle of forms through which it passes shows no terms quite so complex as those which occur in Peronospora and Coleochaete? And, in fact, there are some green organisms, in every respect characteristically plants, such as Chlamydomonas, and the common Volvox, or so-called "Globe animalcule," which run through a cycle of forms of just the same simple character as those of Heteromita. The name of Chlamydomonas is applied to certain microscopic green bodies, each of which consists of a protoplasmic central substance invested by a structureless sac. The latter contains cellulose, as in ordinary plants; and the chlorophyll which gives the green colour enables the Chlamydomonas to decompose carbonic acid and fix carbon as they do. Two long cilia protrude through the cell-wall, and effect the rapid locomotion of this "monad," which, in all respects except its mobility, is characteristically a plant. Under ordinary...
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Add this copy of Discourses to cart. $48.32, new condition, Sold by Booksplease rated 4.0 out of 5 stars, ships from Southport, MERSEYSIDE, UNITED KINGDOM, published 2010 by Kessinger Publishing.
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Add this copy of Discourses: Biological and Geological Essays to cart. $49.62, good condition, Sold by Bonita rated 4.0 out of 5 stars, ships from Newport Coast, CA, UNITED STATES, published 2006 by BiblioBazaar.
Add this copy of Discourses to cart. $48.32, new condition, Sold by Booksplease rated 4.0 out of 5 stars, ships from Southport, MERSEYSIDE, UNITED KINGDOM, published 2004 by Kessinger Publishing.
Add this copy of Discourses to cart. $50.96, good condition, Sold by Bonita rated 4.0 out of 5 stars, ships from Newport Coast, CA, UNITED STATES, published 2004 by Kessinger Publishing.
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Very Good. Very good. One of 1000 copies. Slightly browning. Please Note: This book has been transferred to Between the Covers from another database and might not be described to our usual standards. Please inquire for more detailed condition information.
